insulation upside down -- not!

Two different home inspectors flagged the insulation in the attic of our new home as a problem area on the basis that it was upside down (vapor barrier on top).

Well, turns out this isn't the case. I picked up a piece of it today, and the vapor barrier is definitely down. It's a thick, tough membrane of some sort, probably asphalt paper. There is some other sort of paper on the other three sides. I guess it was to help with itchyness on the install or something.

One more check in the "completed" column!

Still needs more. It looks like it was R-11 when put in and probably only half that now.

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insulation upside down -- not!

Actually, I think there was at one time insulation available that had double sided vapor barrier. This isn't something you're going to find anymore because this is a good way to trap moisture. The function of the vapor barrier should be to keep vapor from passing through one side while allowing it to exit the other.

I had some of this stuff, and the stuff was in attic space with no ventilation. I suspect it was doing little if anything, it had clearlly lost thickness. Moisture degrades fiberglass insulation performance, it will compress which also degrades insulation.. Mine went into the garbage.

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